The invention relates to a reciprocating internal combustion engine having at least one piston.
A reciprocating internal combustion engine is known from DE 33 22 140 A1, which has a crankcase with a cylinder head and a cylinder housing. The cylinder housing has a cylinder bore in which a piston can move back and forth. Two connecting rods are connected via piston pins to the pistons, and on a side thereof facing opposite the piston pins, work together with two crankshafts arranged in a crankshaft housing. The crankshafts are coupled via two gear wheels which engage with each other, in such a manner that the crankshafts rotate at the same rotation speed, but in the opposite direction. Inlet and outlet valves are configured in the cylinder head and are actuated by way of camshafts lying above the valves, with bucket tappets connected between the valves and the camshafts. This reciprocating internal combustion engine is suitable for use as a gasoline engine for powering passenger vehicles, wherein the crankshaft thereof is oriented to lie horizontal.
A V-engine having at least one turbocharger is known from DE 10 2005 056 508 A1. The V-engine is designed as a diesel engine in the outboard motor class for watercraft. A crankshaft connected to the piston of the engine runs upright, and the turbocharger is arranged on a lower end, facing the water line, of a component assembly including a cylinder head and a cylinder housing. An exhaust system, to which the exhaust gas turbocharger is connected, extends along a space formed by the V-shaped cylinders. A drive shaft for a water propeller has a functional connection to the crankshaft.
The problem addressed by the invention is that of developing a reciprocating internal combustion engine, having at least one piston which works together with two connecting rods and with two crankshafts, wherein the reciprocating internal combustion engine is designed as a highly efficient outboard engine for the purpose of driving a water craft, and works with exhaust gas turbocharging when in a diesel configuration. However, the exhaust gas turbocharger as well as the components and systems of the reciprocating internal combustion engine which have a functional connection to the exhaust gas turbocharger should also be arranged in the reciprocating internal combustion engine with a functionally appropriate and space-saving configuration.
According to the invention, this problem is addressed by providing a reciprocating internal combustion engine having at least one piston which moves back and forth in a cylinder bore of a cylinder housing which forms an assembly together with a cylinder head, and which works together with first and second crankshafts, with two connecting rods connected between the piston and the crankshafts, the same rotating about two crankshaft axes and being functionally connected to two synchronization gears of a spur gear box, said synchronization gears being connected to the crankshafts in a torque-proof manner, in such a manner that the crankshafts rotate synchronously in opposite directions. The reciprocating internal combustion engine is a diesel engine with exhaust gas turbocharging, by way of example, wherein the reciprocating internal combustion engine is preferably designed as an outboard engine for a watercraft. The first and the second crankshafts are oriented upright, with crankshaft axes, in such a manner that one of the two crankshafts acts on a drive screw of the watercraft via a transmission. The exhaust gas turbocharger has an exhaust gas turbocharger device with an exhaust gas turbine and a compressor and/or a shaft which carries a turbine wheel and a compressor wheel, which runs perpendicular to the longitudinal dimension of the watercraft. The exhaust gas turbocharger device is directly or indirectly attached on an upper end-face wall of the assembly comprising the cylinder head and the cylinder housing.
The advantages primarily achieved by the invention are that the internal combustion engine having at least one piston with two connecting rods and two crankshafts has excellent functional characteristics, which are optimized by the fact that they work based on a diesel principle and with exhaust gas turbocharging. With this technical characteristic, the reciprocating internal combustion engine is excellently suited as an outboard engine. The exhaust gas turbocharger and/or the exhaust gas turbocharger device, with its shaft which carries the turbine wheel and the compressor wheel, is ideally arranged perpendicular to the longitudinal direction of the watercraft. In this way, bearing loads on the shaft resulting from tilting movements of the watercraft in its longitudinal dimension are largely non-critical.
It is also exemplary how the exhaust gas turbocharger device is attached on the upper end-face wall of the cylinder head/cylinder housing assembly, i.e. distanced from the water line of the watercraft, thereby preventing water from penetrating the exhaust gas turbocharger device and causing operating malfunctions during natural travel of the watercraft. This is supported by the fact that a first angled tube section is included between the exhaust gas inlet side of the exhaust gas turbine and the first end-face wall segment of the cylinder head, and a second angled tube section is included between the exhaust gas outlet side of the exhaust gas turbine and a second end-face wall of the cylinder housing.
Moreover, it must be emphasized that at least one of the two tube sections forms a rigid connection between the assembly and the exhaust gas turbine. As an example, the cylinder head comprises the first upright exhaust channel on the outlet side thereof, via which exhaust gases are guided upward into the exhaust gas turbine and applied to the turbine wheel there.
It is an excellent solution for the internal combustion engine that the first exhaust channel in the cylinder head is configured with the casing which extends over the substantial height of the cylinder head, said casing being designed as a cooling jacket for the exhaust gases. This cooling jacket has a top-notch technical design because it has an inner cooling channel and an outer cooling channel, wherein the inner cooling channel has motor oil flowing through it, and the outer cooling channel has cooling water flowing through it. The inner cooling channel is connected to the motor lubricating oil circulation, and the outer cooling channel is connected to the cooling water circulation of the reciprocating internal combustion engine.
This well thought-out cooling jacket system ensures that when the outboard engine is operated over a longer period of time on idle—when fishing, for observation uses, or the like—the configuration combats the effects of dropping below a dew point. As such, the configuration substantially prevents the exhaust gas present in the region of the first exhaust gas channel from forming a condensate which combines with exhaust gas fractions—for example acid media—which can damage the metal surfaces of a cylinder region adjacent to the exhaust gas channel over time. A drop below the dew point, as mentioned, is prevented by specifically holding the exhaust gas at a moderate temperature, by means of the circulating medium in the motor lubricating oil circulation when the outboard engine is idling, wherein the cooling water flow is thermostatically interrupted in the region of the cooling mantel and/or the outer cooling channel. The second tube section also sets the standard, the same being at least in sections thereof configured with a cooling channel which is connected to the cooling water circulation of the reciprocating internal combustion engine. Accordingly, a comparable measure is implemented on the exhaust gas turbine of the exhaust gas turbocharger device.
Moreover, the configuration advantageously provides the solution that intake air is supplied to the compressor via the air tank adapted upright to the assembly. The air tank is improved by the fact that an intake air suction muffler is integrated into the same. The fact that the medium leaving the compressor arrives in the intercooler and from there is guided into the suction tank of the intake system, the same connected before the cylinder head, constitutes a constructively practical design. In this case, a first flexible connection piece is included between the compressor and the intercooler, and a second connection piece is included between the intercooler, the same connected to the cooling water circulation, and the suction tank. Finally, the arrangement of the flywheels of the crankshafts, the exhaust gas turbocharger device, and the intercooler on the upper end-face wall of the assembly creates compact structural characteristics.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of a preferred embodiment when considered in conjunction with the accompanying drawings.